Kristin E. Gribble

Dr. Gribble is a molecular biologist broadly interested in the evolution, ecology and life history of marine and freshwater plankton. She combines her training in biological oceanography, evolution, and molecular biology to investigate how environment and genetics influence the phenotypic plasticity of life history strategy and morphology to allow adaptation to changes in environmental conditions and to determine evolutionary fitness. By understanding the outcomes induced by specific environmental conditions, the molecular genetic bases of phenotypic changes, and the evolutionary conservation of plasticity, Dr. Gribble’s research enables predictions about the results of changing environmental conditions at scales ranging from the individual to the ecosystem.

Female Brachionus manjavacas. Brachionus rotifers are approximately 500 µm long, are composed of 1000 cells, and have defined digestive, nervous, reproductive and muscular systems. Monognont rotifers like B. manjavacas generally reproduce asexually, with occasional bouts of sexual reproduction. They play a significant role in freshwater and marine ecosystems as consumers of phytoplankton and bacteria and are emerging as an important model system for studying questions of evolution and the biology of aging. Photo credit: Kristin Gribble

Monogonont rotifers as a new model system

Current research in the Gribble lab focuses on studies of evolution, life history, and aging using monogonont rotifers. Rotifers are aquatic invertebrate animals with many advantages as a model in aging and maternal effects research: small size and a two-week lifespan enables high replication and rapid experimentation, transparency allows easy microscopy, clonal propagation permits direct examination of maternal effects without changes in genome, and inducible sexual reproduction enables crossing and traditional genetics. Tools for rotifer research include genomes, transcriptomes, and RNAi. Rotifers are thus a tractable and robust system for investigating many basic biological questions, including the evolution of mate recognition and speciation, the influence of environmental conditions on phenotypic plasticity, and the genetic and epigenetic mechanisms of aging, lifespan-extending interventions, and maternal effects.

Rotifers complement existing invertebrate model systems for studies of human health. As basal triploblast animals, they provide needed evolutionary breath to existing model systems. Importantly, rotifers have not undergone the genome reduction of some other model invertebrates, and thus share more genes in common with humans. Many researchers are beginning to understand that there is value in studying a variety of species to address questions relevant for human health. It is likely that the most robust treatments for aging in humans will be those that work on the broadest range of taxa, acting through evolutionarily-conserved mechanisms.

Life cycle of the monogonont rotifer Brachionus manjavacas. (A) Left, the asexual cycle, in which a female produces clonal diploid eggs by mitosis. Right, the sexual cycle, in which crowding conditions prompt a portion of females in the population to become mictic, producing haploid gametes via meiosis. If haploid gametes are not fertilized, they hatch into diminutive haploid males. Fertilized gametes develop into a dormant resting egg, able to dessicate and overwinter in the sediments. Upon hatching, the resting egg restores the sexual cycle. (B) Amictic (asexual female) carrying a single egg; (C) haploid male; (D) amictic female egg; (E) male egg; (D) dormant resting egg, the product of sexual reproduction. Scale bars for (B) – (E) are 100 µm. Photos: K. Gribble and E. Corey